Résumé
Purpose To compare the CTPA image quality by using contrast agent with different concentration at different injection rate so as to provide suitable contrast agent injection for patients.Materials and Methods A total of 346 patients with suspected acute pulmonary embolism who required to undergo CTPA examination were randomly assigned to high (370 mgI/ml) and low (320 mgI/ml) concentration groups,and each group was further divided into six subgroups with different velocity (3.0,3.2,3.4,3.6,3.8 and 4.0 ml/s).The CT value of the main pulmonary artery,right pulmonary upper lobe artery and right lung under leaf posterior basal segmental artery was measured.Results In the high concentration group,there were no significant differences in pulmonary artery average CT value,noise,single to noise ratio (SNR) and contrast to noise ratio (CNR) among the subgroups with different velocity (P＞0.05).In the low concentration group,the difference was not statistically significant in pulmonary artery average CT value (P＞0.05) among the subgroups with different velocity;however,the noise,SNR and CNR of 3.0 ml/s subgroup had significant differences compared with other subgroups (P＜0.05).There was no significant difference in average CT value of pulmonary artery between the subgroups with the same velocity in the two concentration groups (P＞0.05).In addition,except that the noise,SNR and CNR of 3.0 ml/s subgroup showed significant differences with other subgroups either in high concentration group or in low concentration group (P＜0.05),there were no significant differences in the above-mentioned parameters among other subgroups with the same velocity in both groups (P＞0.05).Conclusion Compared with high concentration contrast agent,the image obtained by using low concentration contrast agent shows no difference in pulmonary artery average CT value but with low iodine flow and iodine flow rate,which can reduce the risks of contrast media induced nephropathy (CIN) and contrast agent extravasation.